Reciprocating compressor

ABSTRACT

A reciprocating compressor is provided. The compressor includes a casing, a linear reciprocating motor provided inside the casing to generate a linear driving force, a cylinder fixed with respect to the casing, and a piston which reciprocates within the cylinder based on movement of the linear motor. An oil pump provided in the compressor includes an oil piston which reciprocates in response to the reciprocating motion of the piston to provide oil to the cylinder and piston.

This application claims priority to Korean Application No.10-2005-0122720, filed in Korea on Dec. 13, 2005, the entirety of whichis incorporated herein by reference.

BACKGROUND

1. Field

The field relates to a compressor, and more particularly, to areciprocating compressor.

2. Background

In general, a compressor converts mechanical energy into compressiveenergy. Compressor may typically be categorized into a reciprocatingtype, a scroll type, a centrifugal type and a vane type. Reciprocatingcompressors may be further categorized into a horizontal typecompressor, and a vertical type compressor.

Due to the need to provide for lubrication of various components,combined with the placement and orientation of the various components ofthe horizontal and vertical type reciprocating compressors, additionalspace is required in the casing to accommodate the oil. Further, in ahorizontal type reciprocating compressor, assembly is complicated due tothe number of components of the oil pump, and oil is not smoothly andcontinuously provided when oil viscosity is high. Likewise, the verticalorientation of the components of a vertical type reciprocatingcompressor makes it difficult to pump oil to the various components,thus decreases reliabilities of the compressor.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will be described in detail with reference to thefollowing drawings in which like reference numerals refer to likeelements wherein:

FIG. 1 is a cross-sectional view of an exemplary horizontal typereciprocating compressor;

FIG. 2 is a disassembled perspective view of an oil pumping unit inaccordance with embodiments as broadly described herein;

FIG. 3 illustrates an oil suction process in accordance with embodimentsas broadly described herein;

FIG. 4 illustrates an oil supply process in accordance with embodimentsas broadly described herein;

FIG. 5 is a cross-sectional view of another exemplary horizontal typereciprocating compressor incorporating an oil pumping assembly asembodied and broadly described herein;

FIG. 6 is a cross-sectional view of another exemplary horizontal typereciprocating compressor incorporating an oil pumping assembly asembodied and broadly described herein; and

FIGS. 7-9 are exemplary installations of a compressor incorporating anoil pumping assembly as embodied and broadly described herein.

DETAILED DESCRIPTION

A reciprocating compressor having an oil pump in accordance withembodiments as broadly described herein is shown in FIG. 1. Although areciprocating compressor, and particularly a horizontal typereciprocating compressor, is presented for ease of discussion, it iswell understood that an oil pumping assembly as embodied and broadlydescribed herein may be applied to other types of compressors and/orother applications which require fluid pumping as described herein.

Descriptions of reciprocating compressors and operation thereof can befound, for example, in U.S. Pat. Nos. 6,875,000, 6,875,001 and6,863,506, which are subject to an obligation of assignment to the sameentity, and the entirety of which is incorporated herein by reference.

The exemplary reciprocating compressor includes a casing 100, areciprocating motor 200 provided in the casing 100 and having alinearly-reciprocating mover 230, a compression unit 300 for compressinga fluid, such as, for example a refrigerant as a piston 320 coupled tothe mover 230 reciprocate together, and a pumping unit 400 installednear the piston 320 of the compression unit 300 for pumping fluid, suchas, for example, oil, contained in the casing 100.

The reciprocating motor 200 includes an outer stator 210 fixed to thecasing 100 and having a winding coil 211 thereon, an inner stator 220provided at an inner side of the outer stator 210 with a predeterminedgap therebetween, and a mover 230 having a magnet 231 positioned in thegap between the outer stator 210 and the inner stator 220.

The mover 230 is fixedly coupled to an outer circumferential surface ofa movable frame 232, the moveable frame 232 having a substantiallycylindrical shape so as to support a plurality of magnets 231 arrangedbetween the outer stator 210 and the inner stator 220. The movable frame232 has two opened sides, with a rear side of the two opened sideshaving a portion which extends towards the center so as to be coupled toa piston 320 of the compression unit 300 by a bolt or other suitablefastener. A passage (not shown) for transferring a refrigerant frominside the movable frame 232 outwardly when the mover 230 reciprocatescan be formed in the movable frame 232. Since the oil pumping assembly400 operates under an air pressure generated by the movable frame 232,the passage may be formed large enough to generate an adequate airpressure.

The outer stator 210 is supported by first and second fixed frames 240and 250, respectively, coupled to both ends of the mover 230, and isfixedly coupled to the casing 100. The inner stator 220 may be press fitto an outer circumferential surface of the front, or first fixed frame240.

The first fixed frame 240 may have a disc shape having an outer diametersimilar to that of the outer stator 220. A cylindrical fixing protrusion241 may protrude back from a center of the first fixed frame 240. Theinner stator 220 is inserted into an outer circumferential surface ofthe first fixed frame 240, and a cylinder 310 of the compression unit300 is inserted into an inner circumferential surface of the first fixedframe 240.

An oil passage 242 for guiding oil inside the casing 100 may be formedat the first fixed frame 240, penetrating the fixing protrusion 241 froma lower side to an upper side. The oil passage 242 guides oil betweenthe cylinder 310 and the piston 320, and then back into the casing 100.A valve seat portion 243 may be connected to the oil passage 242. Thevalve seat portion 243 may have a circular-arc shape, with an oil inlet243 a and an oil outlet 243 b for supporting an oil valve 420 extendingfrom an inner circumferential surface of the fixing protrusion 241 ofthe first fixed frame 240.

An oil pocket 244 in communication with the oil passage 242 may beformed between an inner circumferential surface of the fixing protrusion241 and an outer circumferential surface of the cylinder 310 (includinga front surface of the cylinder 310). The oil pocket 244 is connected toan oil passing hole 312 of the cylinder 310 so that oil can be suppliedbetween an inner circumferential surface of the cylinder 310 and anouter circumferential surface of the piston 320.

The compression unit 300 includes a cylinder 310 which is inserted intoand fixed to the fixing protrusion 241 of the first fixed frame 240, thepiston 320 which is coupled to the mover 230 of the reciprocating motor200 so as to reciprocate in a compression space 311 of the cylinder 310,a plurality of resonance springs 330 and 340 which elastically supportthe piston 320, thereby causing resonance in the piston 320, a suctionvalve 350 provided at an end surface of the piston 320 so as to open andclose a suction channel 321 of the piston 320 thereby restrictingsuction of refrigerant gas, a discharge valve 360 provided at adischarge side of the cylinder 310 so as to open and close thecompression space 311 thereby restricting discharge of the refrigerantgas, a valve spring 370 which elastically supports the discharge valve360, and a discharge cover 380 which covers a discharge side of thecylinder 310 so as to receive the discharge valve 360 and the valvespring 370. The discharge cover 380 is inserted into a cover insertionhole 110 provided at one side of the casing 100.

The oil pocket 244 has a certain volume defined by an outercircumferential surface of the cylinder 310 and an inner circumferentialsurface of the fixing protrusion 241 of the first fixed frame 240. Thecylinder 310 is inserted into and fixed to the fixing protrusion 241 sothat the oil pumping assembly 400 can be installed at the oil pocket244.

The piston 320 is provided with a connection portion 322 which connectsto the movable frame 232. The connection portion 322 is formed as aflange which extends from a rear end of a body portion 321. A suctionchannel 321 a is formed within the shaft of the piston 320. Anotherpassage (not shown) for passing a refrigerant inside the movable frame232 outwardly when the piston 320 is reciprocated can be formed at theconnection portion 322. Since the oil pumping assembly 400 operatesunder an air pressure generated by the movable frame 232, the passagemay be formed large enough to generate an adequate air pressure.

The first and second resonance springs 330 and 340 may be compressioncoil springs. One end of the first, or front resonance spring 330 isfixed to a front side of a connection portion 332 which is coupled tothe connection portion 322 of the piston 320, and another end of thefirst resonance spring 330 is fixed to the second fixed frame 250 thatsupports a rear side of the outer stator 210. One end of the second, orrear resonance spring 340 is fixed to a rear side of the connectionportion 332, and another end of the second resonance spring 340 is fixedto an inner circumferential surface of the casing 100.

A fixed portion 351 (see FIG. 3) is formed as a cut-out at a middleportion of the suction valve 350 so as to be fixed to an end surface ofthe piston 320. An opening/closing portion 352 (see FIG. 3) for openingand closing the suction channel 321 a of the piston 320 by being eitherbent or straightened based on a position of the fixed portion 351 isformed as a cut-out at an outer side of the fixed portion 351.

The discharge valve 360 may be formed of an appropriate material, suchas, for example a plastic material. A compression surface of thedischarge valve 360 is detachably coupled to an end surface of thecylinder 310, thus allowing the valve 360 to be opened and closed. Theouter surface of the compression surface may have a substantiallysemi-spherical shape.

The valve spring 370 may be, for example, a cylindrical or a conicalcompression coil spring. One end of the valve spring 370 is fixed to theouter surface of the compression surface of the discharge valve 360, andanother end thereof is fixed to an inner surface of the discharge cover380. When the valve spring 370 has a conical shape, a relatively widerend of the valve spring 370 may be fixed to the discharge cover 380 toprovide stability.

The discharge cover 380 can form a single discharge space as shown, forexample, in FIG. 1. In alternative embodiments, the discharge cover 380may form a plurality of discharge spaces (not shown). The dischargecover 380 is installed so that a discharge space portion 381 of thedischarge cover 380 can be exposed outwardly through the cover insertionhole 110 of the casing 100. A coupling flange portion 382 of thedischarge cover 380 hermetically coupled to an outer surface of thefirst fixed frame 240 may be formed at an outer circumferential surfaceof an opened side of the discharge space portion 381.

The oil pumping assembly 400 may include an oil piston 410 slidablyinserted into the oil pocket 244 and arranged between an outercircumferential surface of the cylinder 310 and an inner circumferentialsurface of the first fixed frame 240 along a motion direction of thepiston 320, an oil valve 420 for opening and closing the oil pocket 244connected to the oil passage 242 when the oil piston 410 isreciprocated, a valve seat 430 for supporting a rear side of the oilvalve 420, first and second piston springs 440 and 450 installed along amotion direction of the oil piston 410 so as to elastically supportreciprocation of the oil piston 410, and a spring supporting plate 460pressed-fit between an outer circumferential surface of the cylinder 310and an inner circumferential surface of the first fixed frame 240 so asto support the second piston spring 450.

The oil piston 410 may have a substantially cylindrical shape with acertain thickness so that an inner circumferential surface thereof canslidably contact an outer circumferential surface of the cylinder 310,and an outer circumferential surface thereof can slidably contact aninner circumferential surface of the fixing protrusion 241 of the firstfixed frame 240. In certain embodiments, the length the oil piston 410is selected so as to allow the oil passing hole 312 of the cylinder 310to be open to the oil pocket 244, and not blocked by the oil piston 410,during an oil suction stroke to allow for a smooth supply of oil. Theoil piston 410 may be formed of a plastic material, taking intoconsideration friction with the cylinder 310 or the first fixed frame240.

The oil valve 420 may be formed in a ring shape so as to be supported bythe valve seat portion 243 of the first fixed frame 240. One side of theoil valve 420 is provided with a suction valve portion 421, and anotherside thereof is provided with a discharge valve portion 422 which opensand closes in a direction opposite that of the suction valve portion421.

The valve seat 430, which supports a rear side of the oil valve 420, mayalso be formed in a ring shape. A suction hole 431 for opening thesuction valve portion 421 of the oil valve 420 is formed at a lower endof the valve seat 430, and a discharge hole 432 for opening thedischarge valve portion 422 of the oil valve 420 is formed at an upperend of the valve seat 430.

The first and second piston springs 440 and 450 are installed atopposite sides of the oil piston 410, along a motion direction of theoil piston 410. The first piston spring 440 is supported by the valveseat 430, and the second piston spring 450 is supported by the springsupporting plate 460 and press fit or welded between an outercircumferential surface of the cylinder 310 and an inner circumferentialsurface of the first fixed frame 240.

A plurality of air passing holes 461 may be formed at the springsupporting plate 460. The air passing holes 461 receive an innerpressure developed in the mover 230 when the piston 320 is reciprocated,and this received pressure causes the oil piston 410 to smoothlyreciprocate by outwardly applying an inner pressure of the oil pocket244 when the oil piston 410 is retreated.

The oil pumping assembly 400 can be installed between an innercircumferential surface of the first fixed frame 240 and an outercircumferential surface of the cylinder 310. In alternative embodiments,the cylinder 310 may have a double structure. For example, the cylindermay include a first cylinder which receives the piston, and a secondcylinder inserted into an inner circumferential surface of the firstfixed frame. The first cylinder and the second cylinder may be coupledto each other with a gap formed therebetween so as to form an oil pocketin which the oil pumping assembly may be installed.

The compressor as shown in FIG. 1 also includes an oil guiding pipe 260,a suction pipe SP, and a discharge pipe DP.

Operation of the exemplary reciprocating compressor having an oilpumping assembly as embodied and broadly described herein will now beexplained.

When power is supplied to the winding coil 211 fixed to the outer stator210 of the reciprocating motor 200, a flux is generated between theouter stator 210 and the inner stator 220. This causes the mover 230positioned between the outer stator 210 and the inner stator 220 to becontinuously reciprocated due to the resonance springs 330 and 340. Asthe piston 320 is coupled to the mover 230, the mover 230 isreciprocated in the cylinder 310, and a volume of the compression space311 formed between the cylinder 310 and the piston 320 is changed.Accordingly, refrigerant gas is sucked into the compression space 311,compressed, and then discharged.

A semi-hermetic space is formed in the mover 230, and thus a refrigerantfilled in the mover 230 is repeatedly contracted and expanded when themover 230 reciprocates together with the piston 320. As shown in FIG. 3,when the mover 230 moves backward, a pressure inside the mover 230 islowered, causing the first piston spring 440 arranged at a front side ofthe oil piston 410 to be restored to a rest position and the oil piston410 to move backward along with the mover 230 and the piston 320. Avolume of the oil pocket 244 formed a front side of the oil piston 410is increased, thus generating a suction force. The suction force causesthe suction valve portion 421 of the oil valve 420 to open, therebysucking oil from the casing 100 in through the oil passage 242. The oilis dispersed between the cylinder 310 and the piston 320 through the oilpassing hole 312 of the cylinder 310 to provide for lubrication betweenthe cylinder 310 and the piston 320.

As shown in FIG. 4, when the mover 230 moves forward, pressure insidethe mover 230 is increased and oil is moved to the oil pocket 244through the air passing holes 461 in the spring supporting plate 460.When the oil piston 410 moves forward along with the mover 230 due tothe pressure, a pressure in the oil pocket 244 is increased, thusclosing the suction valve portion 421 of the oil valve 420 and openingthe discharge valve portion 422. Through the opened discharge valveportion 422, the oil in the oil pocket 244 is returned to the casing 100through the oil passage 242. In this first embodiment, the oil in thecasing 100 is pumped in response to a pressure difference generated inthe mover 230 when the mover 230 and the piston 320 are reciprocated.

In a second embodiment shown in FIG. 5, the second piston spring 450extends a longer distance, between a rear side of the oil piston 410 andthe connection portion 322 of the piston 320. An oil pumping operationassociated with this second embodiment is similar to that of the firstembodiment. As a reciprocation force of the mover 230 and the piston 320causes the oil piston 410 to reciprocate, a pumping force of the oilpiston 410 is increased and a stability of the oil piston 410 isenhanced due to the longer extension of the second piston spring 450 andits attachment to the connection portion 322 of the piston 320.

In alternative embodiments, the oil piston 410 may be connected to thepiston 320 by a cylindrical body or a rigid body, such as, for example,a plurality of bars, rather than by the second piston spring 450. Thiswould further increase the pumping force and the stability of the oilpiston 410. However in certain embodiments a damping device may also berequired.

A reciprocating compressor having an oil pumping assembly in accordancewith a third embodiment will now be explained. As shown in FIG. 6, frontand rear sides of the oil piston 410 are supported by the first andsecond piston springs 440 and 450. A ring-shaped collision plate 470 isinterposed between the second piston spring 450 and the springsupporting plate 460, and a collision member 323 protrudes from theconnection portion 322 of the piston 320. The collision member 323applies an impact force to the second piston spring 450 via thecollision plate 470.

More specifically, when the piston 320 moves forward, the collisionmember 323 repeatedly collides with the collision plate 470 as it passesthrough one of the holes 461 in the spring supporting plate 460, therebyapplying an impact force to the second piston spring 450 via thecollision plate 470. This impact causes the second piston spring 450 tobe repeatedly contracted and expanded, with corresponding movement ofthe first piston spring 440, thus causing the oil piston 410 to bereciprocated.

The oil pumping assembly 400 reciprocates together with the mover 230and the piston 320, thereby further increasing a pumping force and areliability for the oil pumping operation.

Furthermore, since the oil pumping assembly 400 is installed inside thecompression unit 300, a size of the compressor may be reduced and anentire structure of the compressor may be simplified.

Although an exemplary horizontal-type reciprocating compressor ispresented herein, for ease of discussion, it is well understood thatthis can be equally applied to a vertical-type reciprocating compressor,or other type of compressor, or another application in which this typeof fluid pumping is required and/or advantageous.

More specifically, the oil pumping assembly for a compressor as embodiedand broadly described herein has numerous applications in whichcompression of fluids is required, and in different types ofcompressors. Such applications may include, for example, airconditioning and refrigeration applications. One such exemplaryapplication is shown in FIG. 7, in which a compressor 710 having an oilpumping assembly as embodied and broadly described herein is installedin a refrigerator/freezer 700. Installation and functionality of acompressor in a refrigerator is discussed in detail in U.S. Pat. Nos.7,082,776, 6,955,064, 7,114,345, 7,055,338 and 6,772,601, the entiretyof which are incorporated herein by reference.

Another such exemplary application is shown in FIG. 8, in which acompressor 810 having an oil pumping assembly as embodied and broadlydescribed herein is installed in an outdoor unit of an air conditioner800. Installation and functionality of a compressor in a refrigerator isdiscussed in detail in U.S. Pat. Nos. 7,121,106, 6,868,681, 5,775,120,6,374,492, 6,962,058, 6,951,628 and 5,947,373, the entirety of which areincorporated herein by reference.

Another such exemplary application is shown in FIG. 9, in which acompressor 910 having an oil pumping assembly as embodied and broadlydescribed herein is installed in a single, integrated air conditioningunit 900. Installation and functionality of a compressor in arefrigerator is discussed in detail in U.S. Pat. Nos. 7,032,404,6,412,298, 7,036,331, 6,588,228, 6,182,460 and 5,775,123, the entiretyof which are incorporated herein by reference.

Likewise, the oil pumping assembly as embodied and broadly describedherein is not limited to installation in compressors. Rather, the oilpumping assembly as embodied and broadly described herein may be appliedin any situation in which this type of fluid pumping is required and/oradvantageous.

An object is to provide a reciprocating compressor capable of reducing aproduction cost by reducing a number of components, and capable ofenhancing a reliability with an oil supply device.

To achieve these and other advantages and in accordance with the purposeof the embodiments as broadly described herein, there is provided areciprocating compressor, including a frame for supporting a stator of areciprocating compressor having a linearly-reciprocated mover, andhaving an oil passage, a cylinder fixedly coupled to the frame, a pistonsidably inserted into the cylinder and reciprocating with the mover, andan oil pump installed between the frame and the cylinder so as to beconnected to the oil passage of the frame and reciprocating with thepiston, for generating a pumping force.

Any reference in this specification to “one embodiment,” “an exemplary,”“example embodiment,” “certain embodiment,” “alternative embodiment,”and the like means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment as broadly described herein. The appearancesof such phrases in various places in the specification are notnecessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to affect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, numerous variations andmodifications are possible in the component parts and/or arrangements ofthe subject combination arrangement within the scope of the disclosure,the drawings and the appended claims. In addition to variations andmodifications in the component parts and/or arrangements, alternativeuses will also be apparent to those skilled in the art.

1. A reciprocating compressor, comprising: a casing; a frame fixedwithin the casing and configured to support a stator coupled to alinearly-reciprocated mover; a cylinder fixed to the frame; a firstpiston coupled to the mover and configured to reciprocate within thecylinder as the mover reciprocates; and a pump installed between theframe and the cylinder so as to be in communication with a passageformed in the frame, wherein the pump is configured to reciprocate withthe piston so as to generate a pumping force.
 2. The reciprocatingcompressor of claim 1, wherein the pump is installed surrounding anouter circumferential surface of the cylinder.
 3. The reciprocatingcompressor of claim 1, wherein the pump comprises: a second pistonconfigured to reciprocate within a pocket defined by the cylinder andthe frame, in a motion direction of the first piston; a valve configuredto open and close the passage formed in the frame when the second pistonis reciprocated; and one or more piston springs installed along a motiondirection of the second piston and configured to elastically support areciprocation of the second piston.
 4. The reciprocating compressor ofclaim 3, wherein the second piston has a substantially cylindrical shapesuch that an inner circumferential surface of the second piston contactsan outer circumferential surface of the cylinder, and an outercircumferential surface of the oil piston contacts an innercircumferential surface of the frame.
 5. The reciprocating compressor ofclaim 3, wherein the valve is substantially ring shaped, and wherein thevalve comprises a suction valve portion at one side thereof and adischarge valve portion at another side thereof.
 6. The reciprocatingcompressor of claim 5, wherein the valve is supported by a pistonspring.
 7. The reciprocating compressor of claim 3, wherein the pistonspring is a compression coil spring.
 8. The reciprocating compressor ofclaim 3, wherein the pump comprises an oil pump and the second pistoncomprises an oil piston, and wherein the oil pump is configured to pumpoil through the passage so as to provide for lubrication between thefirst piston and the cylinder.
 9. The reciprocating compressor of claim1, wherein the pump is configured to reciprocate in response to airpressure developed in the mover.
 10. The reciprocating compressor ofclaim 9, wherein the pump comprises: a second piston configured toreciprocate within a pocket formed between the cylinder and the frame,in a motion direction of the first piston; a valve configured to openand close the passage; a plurality of piston springs positioned onopposite sides of the second piston and orientated a motion direction ofthe second piston; and a spring supporting plate positioned between thecylinder and the frame and having a plurality of air passing holesformed therein, wherein the spring supporting plate is configured tosupport one of the plurality of piston springs, and to apply an airpressure difference due to a reciprocation of the first piston to thesecond piston.
 11. The reciprocating compressor of claim 1, wherein thepump is coupled to the first piston so as to reciprocate as the firstpiston reciprocates.
 12. The reciprocating compressor of claim 11,wherein the pump comprises: a second piston configured to reciprocatewithin a pocket formed between the cylinder and the frame, in a motiondirection of the first piston; a valve configured to open and close thepassage formed in the frame; and a plurality of piston springs installedon opposite sides of the second piston and oriented in a motiondirection of the second piston, wherein one of the plurality of pistonsprings has a first end connected to the second piston and a second endconnected to the first piston.
 13. The reciprocating compressor of claim11, wherein the pump comprises: a second piston and configured toreciprocate within a pocket formed between the cylinder and the frame,in a motion direction of the first piston; a valve configured to openand close the passage formed in the frame; a plurality of piston springsinstalled on opposite sides of the second piston and oriented in amotion direction of the second piston; a spring supporting platepositioned between the cylinder and the frame and having at least oneopening formed therein, wherein the spring supporting plate isconfigured to support one of the plurality of piston springs; and aconnection member configured to be slidably inserted into the at leastone opening formed in the spring supporting plate, wherein theconnection member is coupled to the second piston and the first piston.14. The reciprocating compressor of claim 1, wherein the pump performs areciprocation in response to an impact force which occurs when a part ofthe first piston periodically collides with a part of the pump.
 15. Thereciprocating compressor of claim 14, wherein the pump comprises: asecond piston configured to reciprocate within a pocket formed betweenthe cylinder and the frame, in a motion direction of the first piston; avalve configured to open and close the passage; a plurality of pistonsprings installed at opposite sides of the second piston and oriented ina motion direction of the second piston; a spring supporting platepositioned between the cylinder and the frame and having at least oneopening formed therein, wherein the spring supporting plate isconfigured to support one of the plurality of piston springs; and acollision member protruding from the first piston and configured to besidably inserted into the at least one opening in the spring supportingplate so as to periodically collide with the second piston.
 16. Thereciprocating compressor of claim 15, further comprising a collisionplate positioned between one of the plurality of piston springs and thespring supporting plate, wherein the collision plate is configured toapply an impact force to the piston spring when the collision membercollides with the collision plate.
 17. The reciprocating compressor ofclaim 15, wherein the collision member is a compression coil spring. 18.The reciprocating compressor of claim 15, wherein the collision memberextends from the first piston or from the second piston as a protrusion.